Indicating control means for instruments



May 24, 1932. H. H. MAPELSDEN INDICATI NG CONTROL MEANS FOR INSTRUMENTS Filed March 29, 1929 Inventor: Ld H. MapeLsden Ham y Wm HES Attorfieg.

Patented May 24, 1932 I UNITED STATES PATENT OFFICE .HAROLD H. MAPELSDEN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC I TRIO COMPANY, A. CORPORATION OF NEW YORK INDICATING CONTROL MEANS FOR INSTRUMENTS Application filed March 29: 1929. Serial No. 351,092.

The present invention relates to means for positioning, and indicating the position of, the movable control elements of apparatus or instruments, such as radio recelvers and the like. More particularly, the invention relates to means of this character whlch provide a reduction in the rate of movement between a driving and a driven portion thereof, through the medium of a flexible cord wrapped about sheaves on the driving portion and connected with the, driven portion to move it positively, the indicating portion being carried by or connected with either portion, but more specifically the driven portion.

Positioning and indicating means of this general character are well known, one common example of a rotary type being that pro-.

vided in many radio receivers and comprising a rotary driver shaft controlled by a panel knob and connected with a drum on 'a tuning drive to twist. The cord must, however, be

paid out from and be taken up by the driver at substantially the same rate, otherwise backlash or binding occurs. Either of these conditions of operation are extremely undesirable .and particularly so in connection with tuning controls for radio receivers and the like. The end or purpose of such control means is of course the convenient and accurate adjustment of the controlled appa ratus and to this end the indicating means as well as the positioning means is a contributing factor. L

Ordinarily an indicating means for this purpose takes the form of a moving pointer or a moving dial, either illuminated or placed in a position to be readily visible by natural light, and adapted in size and prominence to the size, shape and purpose of the apparatus with which it is used. In radio apparatus for example, the tuning dial or position indicating means has tended toward reduced size or prominence in the general exterior appearance of the apparatus, necessitating artificial illumination either on or through the dial, for the sake of convenience and ready visibility in operation.

Sufficient illumination of small areas for this purpose often tends'to produce the effect of glare. A reduction of this effect to a more comfortable value by a reduction in the visible illumination or by screening has heretofore been accompanied to various degrees by areduction in visibility.

It is therefore the principal object of this. invention to provide an improved indicating control means for instruments which utilizes a cord type of drive and the advantages therein without introducing accompanying disadvantages, and an illuminated "indicating means in which the visible illumination is reduced practically to zero while at the same time the visibility of the indication is greatly increased, whereby easy and accurate adjustment of apparatus 'controlledthereby. is

permitted to a degree heretofore unknown. I

In carrying out the invention, a simple mechanical structure having a single sheave to take up and pay out the cable or drive cord is provided, whereby the latter is un wound from and wound onto the same cylindrical surface and differences in diameter between difierent sheavesare obviated. Thus accurate positioning 'means is provided in connection with an indicating means which utilizes a 'screen'on 'which is projected the image of a moving scale or a portion of the scale Within the limits of the. size of the screen. The screen is adapted in size to the field of View required and to the size of the appara-h tus in which the indicating control means is used.

More fully described, the indicating means includes a projector type of dial which is characterized by the fact that thedial moves through a field of light, the area of the dial be curved or flat and which carries a fixed indicating means suchas a mark in its surface, whereby as the dial moves the image of its scale graduations and indicia moves past I the indicating means and in the same surface.

means of the rotary drum type embodying.

the invention; Fig-'2: is a rear view, of the same in perspective; Figs. 3 and 4 are side views partly in section corresponding to Fig.

1 and on the same scale, of detail modifications; Fig. 5 is a view in perspective and on the same scale as the receding figures, of another detailmodification; and Fig. 6 is a viewof a further detailed modification.

' Referring to Figs. 1 and. 2, 10 is a portion of a control'panel on front wall of an instrument casing in which is, located an instrument control shaft 11. Inthe present example this shaft is journalled in a frameor wall 12 which connects the front panel or wall "with a rear wall 132 p The shaft is mounted in other suitable bearings (not shown) and carries a cup or drum 14 provided with a hub 15 by which it is secured to theshaft. The drum and shaft are driven through the medium of a wrapped flexible cord 16 which in turn is connected with a driver shaft 17. The latter terminates in a control knob 18 on the panel front or other suitable location and is suitably journalled in'front and rear bearing brackets 19 and 20 respectively which are mounted on the wall 12. I

In the present example the apparatus control shaft 11 which may be considered to represent any instrument shaft which it is desired to control, is located within the casing andabgve-the' driver shaft 17, and at a right an 1e thereto. Whilethe invention is notlimi e to an arrangement of this .particular type, it is typical of the usual construction in radio receiving apparatus, which is well known, and is therefore taken by way of example as a suitable construction with which to illustrate the'invention.

The cord is wrapped around the drum to rovide a securev frictional grip upon it, and 1s loo ed through a hole 21 in the drum suitabl ocated to receive it, and through one en of a take- 22 which is located within the drum cu 14 and which is extensible diametrically 0 th cap from afixed pivot stud 23 carried by its p means comprising a spring inner wall 24. In the present example the cord ends are tied together at t e point of connection with the spring or take-up means,

as indicated. The cord is thus positively secured to the drum by the loop" through the hole in a manner, which does not interfere with the s pring connection, which represents anysuitable resilient means for compensating for changes in the Ian hof the cord.

In case that thesha 11 is to 'be' ex tended throughv the drum, two springs, 25 and 26, are provided as shown in Fig. 3. These are secured to suitable pivot studs or to the same pivot stud 23 as shown in the present ,example, and each spring engages the cord in such a manner thatthe springsclear the shaft on either side. In the present example these springs engage the cord at two diflerent oints 27 and 28. The cord ends are joine preferably at one of said points such as point 28 as indicated. The remain ing parts of Fig. 3 are the sameas in Figs. 7

merals. i

Referring again to Figs. 1 and 2, the cord is wrapped about the drum in acircular path 1 and 2 and bear the same reference nuwhereby it engages and. leaves the drum in I two difi'erentplanes. In thepresent example itis wrapped about the drum in theform of a helix and one end 29 leaves the helix to pass about an idler pulley 30 which is positioned to cause. the cord to pass around a single I cylindrical sheave 31 adjacent one end and in I substantially a horizontal plane tangent to the sheave. The sheave is carried byand secured to the inner end of driver shaft 17 in a position thus to receive the cord. The cord is then wrapped about the sheave a few turns and is secured to the sheave in any suitable manner, as bypassing through a diametrical hole 32 in thesheave and shaft, and then continuing to be wrapped aboutt-he. sheave. The cord then leaves the sheave and again passes onto the drum in a plane whichds substantially vertical and tangent to the sheave, and continues about the drumin its helical path. With thisarrangement'the cord is driven by the sheave through the medium of the driver shaft17 and panel knob'18, and causes r, the drum to rotate, thereby driving the con trol shaft 11, and the cord 16 is caused to move in the same helical path about .the drum, whereby its tension is notchanged'perceptibly during the operation of the control shaft by the panelknob 18.

It will be noted in Fig. 1 that while the 'drive sheave 31 and the i I tively close together, the cord is free to move at its ends on-long radii represehted by the distances between its points of contact with the drive sheave 31 and with the drum and idler pulley 30, and that these radii lie in planes tangent to the sheave and at such angles to each other that the cord is guided In passing about the drum in such a manner drum 14 are rela- I that it has no tendency to shift itsposition along the drum as the latter is rotated by it. In the present example the cord assumes a helical path on the sheave since the latter at one end is in tangent relation to the .cord end which leaves the drum in a rectilinear extension of the helix, and tangent at the other end to the cord end leaving the idler pulley.

The idler pulley is mounted upon an arm 33 pressed out from bracket 20 and integral therewith, although it may be mounted upon any suitable means which will hold it in a position to carry and guide the cord in the manner above described.

-As an additional I means for guiding the cord about'the sheave, the latter may be provided with a helical-screw thread as indicated at 34, although in certain cases it will be found that thismay be dis ensed with, since the arrangement of the cor drive is such that the cord will naturally tend to assume a heli-. vcal form about the drive sheave, Likewise,

any other suitable form of connection between the cord and the sheave may be used, such for example as shown in Fig. 4, in which the cord iscaused to bind upon itself in a central groove 35 provided in the sheave 31. This latter arrangement has the advantage that the cord may be secured to the sheave by .an accurate and a simple wrapping operation instead of being passed through a hole or other securing means, and permits a considerable saving in time in manufacture and assembly.

In any case, whether theconnection with v the sheave be with a groove in which a cord is bound upon itself or any other suitable con"- nection, it will be seen that the cord is wound onto and \mwound from the same diameter,

since it is connected with asingle sheave, and

accordingly the cord is' paid out and taken u at the same rate without stretching or binding, which action is supplemented and completed by the maintenance of 'a predetermined path for the cord about the drum and sheave. This arrangement thus provides sitive drive between the panel knob or 0 er control means and the control shaft 11.

Associated withthe control knob 18 is a I panel opening 36. for a position indicating means whereby the relative position of control shaft 11 may be viewed by an operator of the knob 18. In the present example the position indicating means is located in the same plane as and vertically above the driver shaft 17, so that it occupies the same axial space along shaft 11 as the hub 15, the 0 n- P ing 36 bein for this reason directly a ve the control nob 18," although it should be understood that the indicating means may be located in any suitable position in connection with shaft 11.

In this preferred arrangement, however, a high degree of compactness is obtained with the indicating means locatedabout the hub 15 and adjacent to the drum 14.. The "indisource of light may be any suitable means,

such as a small electric lamp 39, 'covered by a shield 40, in which is located an orifice or opening 41. Light from the orifice in projected onto the screen after passing through v the scale and provides an enlarged image 0 minor portion of the scale upon the screen.

In Fig. 2 the image of the scale graduations is indicated on the screen 38. In this figure it will be seen that a mark or marks 42 are placed in the surface of the screen to cooperate with the image of'the scale. .These marks may be of any suitable, form'and in the present example are straight line cuts in the movable member or dial. v

The screen is of any suitable transparent or translucent material, and may be either curved or flat for easy visibility. Inthe prescut example it is curved on a radius about the 1 axis of shaft Hand is rendered translucent by sandjblasting upon one or bothsurfaces, preferably the inner surface. The screen is also preferably of'such color that'the light image of the scale upon it, which'assumes substantially the same color, is pleasing to the eye. Translucent, sand-blasted amber for brown celluloid has been found to give a pleasing color to the image of the scale. v I

The movable member or dial m y assume any; suitable form adapted to carry the scale 1 and to move between the source of light we the screen. In connection with a rotary shaft such as shaft 11, it is circular or segmentalin form, and mounted in connectionfwith the shaft substantially concentric therewith as indicated in Fig. 1. In the present example, the

, dial is mounted upon a se mental disk 43 secured to the drum 14. ne edgefjof the dial lies along the peripheral edge of the segmental disk, and the opposite edgerests upon a supplementary supporting segment 44. The

latter is joined to the segmental" disk, 43 by spacing blocks 45 to which the ends of the dial are secured as indicated at 46 (Fig. 2) -,A long the length of the dial suitable tabs are provided as indicated at 47 (Fig. 1) to hold'it in place.

With the indicating means located in the laneof the driver shaft 17 and the plane of hub 15, the drum 14may be made with any 4 suitable diameter without interfering with the indicating means, and the means provid- ,ing' the source of light for the scale may he placed atany suitable distance from thefsca'le between' the latter and the hub; 7 In the present example, the shield 40 for lamp 39 is secured to wall 12 by means of screws, one of w-The-dial or movable-scale bearing member which is indicated at 48, and the lamp is secured 'to the shield by a springclip 49 carried by its'socket and adapted to seat upon a bracket 5Op1fo jecting from said shield. I The lamp is thus removable 'from'the shield for replacement purposes, and'when positionedon the bracket is so located that its 'filament is opposite the orifice opening 41.

Theshield' is provided about the lamp or between the lamp and the dial in order to prevent ablurring of the image ofthe scale upon the-screen from light reflected through the scale from surfaces about the lamp. In case therefiecting surfaces tend to project light is provided'with a shield as shown, the lamp upon or through the dial even when the lamp may be wholly enclosed in a shield of the type shown in Fig. 5, comprising a tubular body 51,0ne end of which is closed by a flat plate 52haV-ing an orifice opening 53 of any suit "able form,such as a rectangle as indicated, and having an'opposite end open to receive the lamp39, and its connected leads 54 which lead to any suitable source of electrical energy (not; sl1ow v h 1 may be of any suitable sheet material having *transparent or translucent; and opaque or I semi-opaque, portions defining graduations andindi'cia. That is, it may be opaque or semi opaque in body with'translucent, trans parent or open graduations and indici'a', or *itmay be'translucent or transparent i body with opaque or semi-opaque gr'aduations and it may be of metal and therefore opaque, perindicias For example, the scale member may beof white or transparent'cellu'loid black-1 ened'except for graduations and i-ndicia, or

. 'forated to proyide open graduations and in- 5dicia.':' -The preferred form is the latter; since the perforations permit greater strength of light to fall upon thesjcreen and the rnetal is fully opaque sothat the contrast *betwee'n'theopen' graduation's and opaque {body of the scale members is as much asmay ""beobtaine'd. v

The';'scale' jmember is (if such length that Tit"maybe graduated to covei the full oper-' ating movement of any apparatus with which "it is used, and in connection with the usual radio apparatus is slightly over 180 in 'an-J F gul'ar length to cover the 180 movement" of Tithe tuning 'me'ans involved therein. In the drawings, the scale member' and driving means-1s shown at its zero-setting and in Y readiness to be turned in a clockwise direcj tion, as'viewed in Fig. 1, theknob 18 being 'turne'd 'for this purpose toward the observer.

"Thelimage of the scale as shown in part in Fig. 2,1noves into and o'ut of view across the screen and in the same direct on as the scale "moves. The position; of the d al or scale memberfmay be determined "by the relation of theimage on the screen to the marks {12 p'r'ovided in or adjacent-"thescrecn surface.

' quiredi In con ection" with radio receivers the positioning means is provided in connection with driver sha'ft"17,whereby an operating force tending to move the dial beyond its limits is met substantially atits source.

- This stop means may-be of any suitable type" connected with driver shaft 17 or control knob 18, and inthe present example includes a collar 55 freely rotatable upon driver shaft 17 adjacent "bracket 19, the collar being provided with an axially extending stud 56 and a radially extending stud 57. The latter stud is adapted to engage an axially extending stud 58 carried by bracket 19, and the former stud56 being adapted t0v engage a'ra dially extendingstud 59 carried by driver shaft 17. With this arrangement driver shaft 17 is permitted to make substantially two full revolutions 'between stops, which with the ratio of the diameter of the sheave 31t o the diameter of the drum'l l, is'just sufin'g range of 180. I

nost'rain placed -ficient to carry the scale through its operat- From the foregoing description it will be i seen that not only is the] control ofanapparatus facilitated by the positioning means provided, but the indicatingmeaiis is also a'cooperating factor-in the effective control of "said apparatus. -The illumination of the dial is'by this arrangement greatly increased,

since the light falls directly on orthrough the dial, while the visibleillumination of the 'dial is reduced substantially to zero. The scale "is not Viewed by'the eye but only its image on *a' screen of a color which 'is pleasing and restful to the eye. There is no glare and there is .no errorin reading due to parallax, since the I image and the mark with which it is compared are inthe same observed surface:

. It'will be -seen that by spacing the'screen 38 atan increasing distance from the scale, the image of thescale may be proportionately increased in'size, whereby the scale is enlarged to any suitable size for any purposesince the scale directly intercepts and -re-. 'ceived-the image. Likewise, the size of the scale image maybe reduced insize by moving the screencloser tothe'dial; thus permitting one size of scale graduations' and indicia to'be adapted to aplurality of uses,

wherein varying degrees of visibility are ref this is a'd'esirab e feature, in thatwithout change of construction the size of the dial indications may begchanged to adaptthe inist ' image of said scale,

shown and described and indicating means dications to meet the requirements of the observer. It will also be seen that the control knob and screen are associated or ar ranged upon the panel whereby the screen may be observed while operating the knob.

It will beeobserved that in theembodiment herein, the positioning in accordance with the invention, is simple in construction and compact, whereby it may be mounted in apparatus providing a small space vfor the operating means, such as modern compact radio apparatus for example. Furthermore, the construction is readily adapted for easy manufacture at low cost, since it includes parts which are readily stamped and pressed from sheet metaL.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination of a movable member having opaque portions defining a scale through which light may be passed, a source of light and a shield therefor having an orilice arranged to project light through said scale to provide a projected image thereof, a translucent screen located in spaced relation to said memberfor directly intercepting and receiving the projected image of the scale, and means incuding a panel for holding the screen in a fixed position to be viewed.

2. In an indicating control means for instruments, the combinationof a movable dial having translucent and opaque portions defining a scale, a source oflight and a shield therefor having an orifice for projecting light through said dial toprovide a projected image of said scale,

dial and arranged diimage of said scale.

struments, the combination of a movable dial having translucent and opaque portions defining a scale, a source of light and a shield thereforhavin'g an orifice for projecting light through said dial to provide a projected a screen located in spaced relation to said dial for directly intercepting and receiving the dial between said light projecting means and said screen.

4. In a radio receiver, the combination with a movable control element therefor, of

a movable scale member, said member being age of said scale.

5. ,An instrument control means including and a screen located in spaced relation to said rectly to intercept and receive the projected I projected image of said scale, and means for positively moving said in combination, a scale member having transof light and screen and serving as the sole light-ray modifying means a relativelythin movable member having portions permitting passage of light for forming graduations and light obturating portions forming a back ground for said graduations, whereby the shadow ofisaid light obtura-ting portions is thrown on said screen, said screen being positionedrelatively close to said movable memher, and said source of light being positioned at such distance therefrom as will form on said screen a well defined, substantially mag-- nified image ofssaid graduations.

7. A dial device for indicating the adjustment of an instrument to which it is connected having, in combination, means forming a source of concentrated light, a translucent screen, and interposed between said source of light and screen and serving as the sole lightray modifying means a rotatable, laterally curved, relatively thin member having portions permitting passage of light-for forming graduations and light obturating portions forming a background for said graduations,

whereby the shadow of said light obturating portions is thrown on saidscreen, said screen being positioned relatively close to said rotatable member at the convexside thereof, and said source of light being positioned at the concave side thereof at such distance therefrom as will form on said screen a well defined, substantially magnified image of said graduations.

8. A dial, mechanism having, in combina tion, a movable relatively thin member "for indicating the degree of movement of the den5 vice to which said member is connected, said member having portions permitting passage of light for forming graduations and light obturat'ing portions forming a background for said graduations, 'a lamp at one side of said member, a translucent screen at the opposite side of said member, said member being presented in a lation tothe plane of said screen, thereby to eifectthe projected images of said graduations'onsaid screen so that the graduations visible on saidscreen will be clearer at a given point than at any other point. l

In witness whereof, I have hereto set my hand this 28th day of March, 1929.

' HAROLD H. MAPELSDEN.

curved surface with re- 

